Aversa Raffaella, Apicella Davide, Perillo Letizia, Sorrentino Roberto, Zarone Fernando, Ferrari Marco, Apicella Antonio
Department of Materials Engineering and Production, University Federico II, Naples, Italy.
Dent Mater. 2009 May;25(5):678-90. doi: 10.1016/j.dental.2008.10.015. Epub 2009 Jan 17.
In healthy conditions, modeling and remodeling collaborate to obtain a correct shape and function of bones. Loads on bones cause bone strains which generate signals that some cells can detect and respond to. Threshold ranges of such signals are genetically determined and are involved in the control of modeling and remodeling. The present study aimed at assessing the deformations transferred to surrounding bone by endodontically treated maxillary central incisors restored with endocrowns made up of high or low elastic modulus materials.
The solid model consisted of a maxillary central incisor, the periodontal ligament (PDL) and the surrounding cortical and cancellous bone. Both composite and alumina endocrowns were simulated under load and compared to a sound tooth. Dynamic non-linear analyses were performed to validate discretization processes. Non-linear analyses were performed on teeth and surrounding bone to estimate strain variations according to restorative techniques.
Strain values in cortical bone, spongy bone, alveolar cortex and tooth were evaluated. PDL allowed models to homogeneously transfer loads to bone. Strains developing in highly rigid restorations were estimated to activate bone modeling and remodeling.
The higher deformability of composites could enable restorative systems to transfer limited strains to compact and spongy bone of tooth socket. Although composites could not prevent the physiological resorption of the alveolar bone, they could successfully reduce strain arising in tooth socket when compared to alumina. The PDL prevented bone to undergo high deformations, resulting in natural flexural movements of teeth.
在健康状态下，骨的塑形和重塑共同作用以获得骨骼正确的形态和功能。作用于骨骼的负荷会引起骨应变，从而产生一些细胞能够检测并做出反应的信号。这些信号的阈值范围由基因决定，并参与塑形和重塑的控制。本研究旨在评估用高弹性模量或低弹性模量材料制成的嵌体冠修复的上颌中切牙根管治疗后传递至周围骨的变形情况。
实体模型包括上颌中切牙、牙周韧带（PDL）以及周围的皮质骨和松质骨。在加载条件下模拟复合树脂和氧化铝嵌体冠，并与健康牙齿进行比较。进行动态非线性分析以验证离散化过程。对牙齿和周围骨进行非线性分析，以根据修复技术估计应变变化。
评估了皮质骨、松质骨、牙槽皮质和牙齿中的应变值。牙周韧带使模型能够将负荷均匀地传递至骨。估计在高刚性修复体中产生的应变会激活骨的塑形和重塑。
复合材料较高的可变形性可使修复系统将有限的应变传递至牙槽窝的密质骨和松质骨。尽管复合材料无法阻止牙槽骨的生理性吸收，但与氧化铝相比，它们能够成功降低牙槽窝中产生的应变。牙周韧带可防止骨发生高变形，从而导致牙齿自然的弯曲运动。
